EP0690704A1

EP0690704A1 - Orthesis or exoprosthesis for the human knee joint

Info

Publication number: EP0690704A1
Application number: EP94908313A
Authority: EP
Inventors: Dietmar Kubein-Meesenburg; Hans NÄGERL
Original assignee: Kubein-Meesenburg Dietmar Prof Dr; Nagerl Hans Dr; Theusner Joachim Dr
Current assignee: Nagerl Hans Dr; Theusner Joachim Dr
Priority date: 1993-03-24
Filing date: 1994-02-16
Publication date: 1996-01-10
Anticipated expiration: 2014-02-16
Also published as: AU6140294A; US5800370A; ATE170735T1; WO1994021200A1; DE4309577A1; EP0690704B1; DE59406889D1

Abstract

The present invention relates to an exoprosthesis for the human knee joint consisting of a thigh section (1) securable to the human thigh and a lower leg section (6) securable to or capable of replacing the human lower leg. The lower leg (6) and thigh (1) sections are coupled by a four-joint arrangement consisting of two parallel partial joints, a medial (11) and a lateral (10) joint, having the joint geometry of a joint chain with two axes of articulation (Mu, Mo; Lo, Lu) (dimeric joint chain). The joint geometry of the medial joint (11) takes the form of a reversed dimeric joint chain in which the articulation axis Mu of the lower leg section (6) is offset towards the thigh section (1) with respect to the articulation axis Mo of the thigh section (1) and the geometry of the lateral joint (10) takes the form of an extended dimeric chain in which the articulation Lu of the lower leg section (6) is offset towards the lower leg (8) with respect to the articulation axis Lo of the thigh section (1) . The two articulation axes of the lateral (10) and medial (11) joints are coupled together by a coupling member (13, 14).

Description

ORTHESIS OR EXOPROTHESIS FOR THE HUMAN KNEE.

The present invention relates to an exoprosthesis for the human knee joint.

The known exoprostheses for the human knee joint are multi-joint arrangements using ball joints and / or hinge joints. However, joint arrangements of this type are not suitable for reproducing the actual joint function of the human knee joint in a substantially lifelike manner, so that these exoprostheses cause considerable walking disabilities.

The object of the invention is to create an exoprosthesis for the human knee joint which has a joint function which essentially corresponds to the natural joint function of the human knee.

This is achieved according to the invention in that the exoprosthesis consists of a thigh part which can be connected to the human thigh and a lower leg part which can be connected to or replaced by the human lower leg, the lower leg part and the Thigh part is connected by a four-joint arrangement, which consists of two parallel partial joints, namely a medial joint and a lateral joint, each of which has the joint geometry of a joint chain with two joint axes (dimer joint chain), the joint geometry of the medial joint as a rollover, dimer Articulated chain is formed, in which the joint axis of the lower leg part is offset in the direction of the thigh part with respect to the joint axis of the thigh part, and the joint geometry of the lateral joint is designed as a stretched, dimeric chain, in which the joint axis of the lower leg part is opposite the joint axis of the Thigh part is set in the direction of the lower leg and the two joint axes of the lateral joint and the medial joint are each articulated to one another by means of a coupling member. The medial joint is pressure stable due to its joint geometry, whereas the lateral joint is unstable. The configuration according to the invention ensures that the exoprosthesis only has freedom of movement in one joint plane and, at the same time, high mechanical stability is achieved, with a wide range of variations being available for adaptation to individual circumstances.

Advantageous embodiments of the invention are contained in the subclaims.

The invention is explained in more detail with reference to the exemplary embodiments illustrated in the accompanying drawings. Show it:

Fig. 1 is a front view of an exoprosthesis according to the invention attached to the human leg Condition, partly cut,

2 shows a side view according to arrow II in FIG.

3 shows a side view of a further embodiment of a prosthesis according to the invention in the state attached to the human leg,

4 shows a section through a further embodiment of an exoprosthesis according to the invention as a replacement for the human knee joint,

FIG. 5 shows a side view of the inventive exoprosthesis according to FIG. 4 in the direction of arrow V.

6 shows a schematic diagram of the joint geometry in a side view according to FIG. 2

As can be seen from FIG. 1, an exoprosthesis according to the invention consists of a thigh part 1, which in the illustrated embodiment consists of two thigh splints 2, 2a, each on the medial (inner) and lateral (outer) side of a thigh 3 of a human Leg 4 run and are connected to one another by transverse rails 5 which encompass the thigh 3. The lower leg part 6 is formed from two lower leg rails 7, 7a, specifically on the medial and lateral side of a lower leg 8 of the leg 4, which are connected by transverse rails 9, the transverse rails 9 in turn encompassing the lower leg 8. The lateral upper and lower leg splint 2, 7 and the medial thigh and lower leg splint 2a, 7a are each marked by a Two-joint, namely the lateral joint 10 and the medial joint 11, which are adjacent to one another in two parallel planes, ie the two parallel joints arranged in parallel form a four-joint arrangement. The lateral joint 10 and the medial joint 11 have the joint geometry of a joint chain with two joint axes, a so-called dimeric joint chain. Here, the lateral joint 10 is stretched as axes, dimeric link chain with the two Gelenk¬ L _0, L is _U, the articulation axis L ₀ is hingedly connected to the joint axis L _and by a coupling member. 13 The hinge axes L ₀ and L _u have the rotation centers M. and M ₂ and run perpendicular to the sagital plane or perpendicular to the swivel plane of the leg 6. The hinge axes L ₀ and L _u are in the stretched position shown at a distance from each other, namely L ₀ offset in the direction of the thigh 3 and the articulated axis L _u offset in the direction of the lower leg. The coupling members 13 and 14 are arranged parallel and vertically in the standing position.

The medial joint 11 is designed as a rollover, dimeric joint chain, the joint axis M _{u of} the lower leg splint 7a being offset in the direction of the thigh 3 with respect to the joint axis M _{0 of} the thigh splint 2a, with reference to the plugged one shown Leg position. The two joint axes M _u and M ₀ are articulated to one another by a coupling member 14. Constructively, this arrangement is expediently realized in that the two rails 2a and 7a overlap on the end side, and in the overlap region between the rails 2a, 7a the coupling member 14 is arranged and at one end with the hinge axis M _u and at the other end is articulated to the hinge axis M ₀ . So that the over- lapping arrangement is possible, the lower leg splint 7a is cranked in the medial direction or the thigh splint 2a in the lateral direction. It can also be seen that the joint axis M _{0 of} the thigh splint 2a of the medial joint 11 is expediently offset by the offset dimension Δ x in the direction of the thigh part relative to the joint axis L _{0 of} the thigh splint 2 of the lateral joint 10. Furthermore, it can be seen from the side view according to FIG. 2 that the joint axis L _{0 is} expediently offset from the joint axis M ₀ in the posterior direction by the offset dimension Δy. In the stretched dimeric chain of the lateral joint 10, the center of rotation M ₂ in L _u moves relative to the center of rotation M. in L ₀ or vice versa on a circular path around M ₁ with the radius R, which is the distance between the axes L. ₀ and L _u corresponds. R is the relevant length of the coupling link 13. In the overturned dimeric chain of the lateral joint 10, the rotation center M ₃ in M _u moves relative to the rotation center M ₄ in M ₀ or vice versa on a circular path around the rotation center M ₃ with the radius RL , which corresponds to the distance between the axes M _u and M ₀ , which in turn represents the relevant length of the coupling element 14. In the case of the above circular path movements, rotary movements also occur around the respective centers of rotation M. to M ₄ .

While FIGS. 1 and 2 show how the exoprosthesis according to the invention is designed to encircle the human, sick knee on both sides, FIG. 3 shows an embodiment in which the four-joint arrangement according to the invention, on one side on the human , sick knees, for example laterally, is attached. The same parts as in FIGS. 1 and 2 are provided with the same reference numerals. The design of the lateral joint 10 corresponds to the 1 and 2. The medial joint 11 is formed by an extension 16 on the lower leg splint 7, which overlaps the bearing end of the thigh splint 2 and, seen laterally, ends in the direction of the human knee behind the bearing end of the thigh splint 2, so that the lateral joint 10 and the medial joint 11 are arranged parallel to one another, the coupling member 14 of the medial joint 11 also being seen in the direction of the knee behind the thigh splint 2 via the joint axis M ₀ to its bearing attachment.

FIGS. 4 and 5 show an embodiment of an exoprosthesis in which the human knee joint is completely and permanently replaced, whereas the embodiments according to FIGS. 1 to 3 are only intended to serve as auxiliary devices as long as the existing one human knee itself is not able to perform the normal joint function. 4 and 5, the same parts as in FIGS. 1 to 3 are again provided with the same reference numerals. The lateral joint 10 and the medial joint 11 are in this case fastened to a thigh stump 20 which can be implantable and to a lower leg stump 21 which can be part of a lower leg prosthesis. The lateral joint 10 is formed by a bearing extension 22 formed on the thigh stump 20 and a bearing extension 23 formed on the lower leg stump 21, which are connected in an articulated manner via the coupling member 13, for which purpose the coupling member 13 is connected to the bearing extension 22 via the joint axis L ₀ and via the joint axis L _{u is} articulated to the bearing extension 23. The medial joint 11 is formed by a joint extension 25 on the stump 20 and a joint extension 26 on the lower leg 21, the joint extension 26 overlapping the joint extension 25 and between - 1 -

see the articular process 25 and the bearing process 22. The coupling member 14 is arranged spatially between the two articular processes 25, 26 and is articulated to the free end of the articular process 26 via the articulation axis M "and to the free end of the articular process 25 via the articulation axis M ₀ . As can be seen from this illustration, the lateral joint 10 is advantageously offset posteriorly from the medial joint 11 by the dimension Δ y and the joint axis M ₀ is offset from the joint axis L ₀ by the offset dimension ^ x in the direction of the thigh .

Furthermore, it is within the scope of the invention if the coupling members 13, 14 are fastened so that they can be exchanged so that the joint geometry can be changed and adapted to the respective specific conditions using the other prosthesis parts by changing the length of the coupling members 13, 14. It can also be provided according to the invention that the length of the thigh and lower leg splints is variable. Correspondingly, the joint extensions according to FIGS. 4 and 5 can also be designed to be variable in length. In addition, the bearing point of the joint axes L ₀ , L _u and l, M _{c can also be designed} such that they can be arranged so as to be variable with respect to their height or lateral bearing point.

FIG. 6 shows the geometric relationships of an exoprosthesis according to the invention in a side view according to FIG. 2. The two joints 10, 11 are installed according to the invention in such a way that their four-joint axes L ₀ , L _u and M ₀ , M "are parallel run to each other in two parallel planes, and that the lateral joint 10 is occupied a little posteriorly, ie backwards, relative to the medial joint 11 by the dimension A y. Such a joint structure represents a four-joint, the straight line marked with F representing the thigh part and the straight line marked with T forming the lower leg part. In the following consideration, it is assumed that the thigh part F is fixed and forms the frame. The relative movement of the lower leg with respect to the thigh is represented by the movement of the part T. Since the length of T is greater than the sum of the length of the coupling members 13, 14, the joint axis L _{0 can} emerge from the thickly marked initial position only move posteriorly. The joint axis M _u can move both anteriorly and posteriorly. In both cases, however, the distal extension of T, the lower leg, swings backwards. Both cases represent two possible squat movements, each of which is inevitable. During the anterior movement of the joint axis M _{u, it} moves further past the anterior dead position (coupling member 14 and straight line T form a straight line and coincide). The lower leg part can then the thinly drawn position a. take in. During the posterior movement of l, this hinge axis reaches its posterior position in the posterior dead position (coupling member 13 and straight line T form a straight line and coincide, drawn position h.). As a result of the further movement, M _u then moves in the anterior direction. This migration takes place so slowly that with this further swiveling of the lower leg part the joint axis M _u appears to remain in place (position b ₂ of T). In any case (a .., b., B ₂ ) the lower leg is pivoted backwards. The artificial joint is thus designed in such a way that under the effect of the non-positive, compressive forces, the lower leg can only pivot backwards. Since the medial joint 11 is offset by the dimension A x with respect to its joint axes M _u and M ₀ in the direction of the thigh, the maximum oscillation angle μ max. of the joint that corresponds to the maximum flexion angle of the human knee can be influenced posteriorly. There is a law that the larger the offset A x, the smaller the maximum oscillation angle μ max. fails. The offset dimension x is preferably chosen such that the connecting distance F from L ₀ to M _u includes an angle α with respect to the horizontal line which is between 0 and 45 °: 0 <α <45 °. It is also within the scope of the present invention to arrange the lateral joint 10 and the metal joint 11 in such a way that the planes are spatially inclined to one another through their coupling members 13, 14, which results in a spherical movement sequence.

Claims

Expectations :

1. Exoprosthesis for the human knee joint consisting of a thigh part (1) which can be connected to the human thigh and a lower leg part (6) which can be connected to or replaced by the human lower leg, the lower leg part (6) and the Thigh part (1) is connected by a four-joint arrangement which consists of two parallel partial joints, namely a medial joint (11) and a lateral joint (10), each of which has the joint geometry of a joint chain with two joint axes (M _u , M ₀ ; L ₀ , L _u ) (dimeric link chain), the link geometry of the medial link (11) being designed as a rollover, dimeric link chain, in which the link axis M _{u of} the lower leg part (6) towards the upper leg part (1) is offset relative to the joint axis M _{0 of} the thigh part (1), and the joint geometry of the lateral joint (10) is designed as an elongated dimer chain, in which the G Articulation axis L _{u of} the lower leg part (6) is offset in relation to the articulation axis L _{c of} the thigh part (1) in the direction of the lower leg (8), and the two articulation axes of the lateral joint (10) and the medial joint (11) each by means of a coupling member (13, 14) are hinged together.

2. Exoprosthesis according to claim 1, characterized in that the thigh part (1) consists of two thigh rails (2, 2a) which extend on the inner and outer side of a thigh (3) of a human leg (4) and through transverse rails (5) are connected to one another, which encompass the thigh (3) and the lower leg part (6) is also formed from two lower leg rails (7, 7a), namely on the medial and lateral side of a lower leg (8) of the human leg (4), the rails (7, 7a) being connected by transverse rails (9) which enclose the lower leg (8).

3. Exoprosthesis according to claim 1 or 2, characterized in that the joint axes (L ₀ , L _u and M _u , M ₀ ) run parallel to one another in two parallel planes and that the Lateral¬ joint (10) relative to the medial joint (11) after pos¬ terior, ie to the rear, offset by the amount Δ y.

4. Exoprosthesis according to one of claims 1 to 3, characterized in that the medial joint (11) relative to the lateral joint (10) in the direction of the thigh (3) with respect to its joint axes M _u and M _{0 is} offset by the dimension Δ _x , wherein the size of this offset the maximum oscillation angle μ max. of the joint can be influenced posteriorly.

5. Exoprosthesis according to one of claims 1 to 4, characterized in that the Two joints, the lateral joint (10) and the medial joint (11) are jointly arranged on the lateral side of the human knee, the medial joint (11) being formed by an extension (16) on the lower leg splint (7) that overlaps the bearing end of the thigh splint (2) in the direction of the thigh and, viewed laterally, ends in the direction of the human knee behind the bearing end of the thigh splint (2), so that the lateral joint (10) and the medial joint ( 11) are arranged parallel to one another, the coupling member (14) of the metal joint (11) also being articulated in the direction of the knee behind the thigh splint via the bearing axis M _u to its bearing shoulder.

Exoprosthesis according to one of claims 1 to 5, characterized in that the lateral joint (10) and the medial joint (11) are each attached to a thigh stump (20) and a lower leg stump (21) which is part of a lower leg prosthesis , wherein the lateral joint (10) is formed by a bearing extension (22) formed on the thigh stump (20) and a bearing extension (23) formed on the lower leg stump (21), which are connected in an articulated manner via the coupling member (13), and the medial joint (11) is formed by a joint extension (25) on the thigh stump (20) and a joint extension (26) on the lower leg stump (21), the joint extension (26) overlapping the joint extension (25) and between the joint extension (25) and the bearing extension (22), and the coupling member (14) is arranged between the two joint extensions (25, 26).